Specimen slides such as Pap smears are examined by microscope users for specific types of events such as cancer cells. These events are, however, relatively rare and once found are difficult to re-locate for confirmation by others. This is a severe drawback, since an important requirement for cancer screening laboratories is certification by a pathologist, with the need for independent relocation.
The prevailing method in aiding relocation is the placement of an ink dot on the slide near the location of the event. This method has proven to be awkward, time consuming and inaccurate. In addition, with this method, it is not possible to ascertain if the entire specimen area of the slide has been uniformly examined or if the areas of the specimen have or have not been scanned. It is accordingly often the case, that if the user is interrupted, it is necessary to restart slide examination. With microscope examination of items, such as diamonds or other types of jewels, for identifying characteristics, the use of ink dots can actually detrimentally mar the appearance of the item.
Ink dot marking and other similar location methods also do not provide any information at all regarding the rate (an important quality control factor) at which each area has been examined. The dots merely function as markers and cannot provide a description of the event or any scan history record. As a result of the realization that cancer screening is inaccurate, because areas are missed, there is a major effort in place to improve the quality of screening laboratories by requiring re-screening of randomly selected slides.
In accordance with current ink dot marking practice, slides are marked with ink dots, at particular events of interest, with electrically controlled pens or marking, with the push of a button. These marking devices are exemplified by those disclosed in U.S. Pat. Nos. 3,600,057; 4,262,426; 4,690,521; and 5,076,679.
More sophisticated location methods, with event location coordinates, include those, such as disclosed in U.S. Pat. No. 4,190,314, wherein microscope slides or cover slips are marked with a grid of lines which is visible through the microscope lens. However, it is necessary to continually interrupt scanning to write down coordinates. Furthermore, no scan history is possible and special slides are required for each specimen.
Similarly, U.S. Pat. Nos. 1,996,141 and 3,514,180 provide viewable stage coordinates and modern microscopes are available with scales to determine stage position However, there is no scan history and the user must stop scanning to interpret the scale and write down the coordinates of events of interest.
Motor controlled stage or slide holder devices such as embodied in U.S. Pat. Nos. 3,999,047; 4,012,112; 4,833,382 and 5,072,382, generally provide a visible indicia on a slide for observation by the user with coordinates set into the device. The slide is moved in a meander pattern until an event of interest is discovered, at which point the slide is stopped and the position is recorded. While this provides both recording of position and a recording of scan history, it is limited by the need for the user to wait until the event comes into the field of view to stop the meander, rather than by controlling movement by hand. Such devices, besides being very expensive, also interfere with normal use of the microscope and the motion control devices thereof detract from the feel of a normal microscope stage positioning control.
Very recently, a new device has been developed which utilizes personal computers to record slide data. This device, with video input to specially modified microscopes, superimposes the display of a computer output on the microscope field for viewing by the user. A mouse is used to mark off events of interest. The device is described in Cytometry, vol. 13, pages 109-166 (1992) and Analytical & Quantitative Cytology & Histology, vol. 14, August 1992. While useful, such devices are inherently expensive and complex in requiring extensive modification of microscopes, thereby limiting their utility with respect to different field-available microscopes. As a result, widespread reviewing capability is severely restricted.